Fire control instrument



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INI/ENTOR Ha/mzbal Ford March 9, 1948. H. c. r-'oRD FIRE coNTRoL INSTRUMENT Fi 1ed July 21, 1928 Nimh 9,1948. H. c. man 2,431,463

FIRE CONTROL INSTRUMENT Filed July 21. 19ersA 2 sneetsneet 2 mvg/WOR Hanniba I Ford Patented Mar. 9, 1948 FIRE CONTROL INSTRUMENT Hannibal C. Ford, Jamaica, N. Y., assigner to Ford Instrument Company, Inc., Long Island City, N. Y., a corporation of New York Application July 21, 1928, Serial No. 294,496

37 Claims.

This invention relates to fire control instruments and more particularly to mechanism, such as a sighting device, adapted to be maintained in a predetermined relation to a line to a target to serve' as a directing and reference element for use with other mechanisms for predicting future positions of the target in order that the guns may be properly aimed for their projectiles to hit the target. While the instrument is especially intended for use in systems for controlling ordnance used against aerial targets it may be employed for ordnance used against surface targets.

In my co-pending application, Serial No. 295,437, led July 26, 1928, I have shown apparatus of this character which when properly adjusted will automatically maintain a mechanism in a predetermined relation to a line to a target so that the operators of the apparatus are relieved of the necessity of performing the operations of following the target in train and elevation except insofar as they may be required to make adjustments from time to time to correct for changes in the motion of the target.

While in my co-pending application means are provided for compensating for changes in course of the craft on which the apparatus may be mounted, no means are provided for compensating for angular movements of the craft, such as roll and pitch, which would cause continual deviations of the mechanism from the predetermined relation to the line to the target.

It is accordingly a general object of this invention to provide an instrument which when properly adjusted will maintain a mechanism, such as a sighting device, in predetermined relation to a line to a target irrespective of the roll and pitch of the craft on which it is mounted. In other words, the instrument provides a stable plane of reference to serve as a datum from which the movements in elevation of the target may be determined for use in mechanism for predicting future positions of the target. The motion of the craft relative to this stable plane may be divided into two components, roll and cross-roll. Roll, designated L, is the inclination of the deck of the craft in the plane of re to a true horizontal plane. VCross-roll, `designated Z is the inclination of the deck to a horizontal plane at 90 to the plane of lire.

More specifically the stable plane of reference is maintained by means of a gyroscope designated herein as a level gyroscope. The mechanism is maintained in a predetermined relation to a line to the target by a second gyroscope, designated herein as the angle gyroscope, which is caused to precess at the required rate for this purpose by forces applied to it in accordance with the rate of change of the movement of the line to the target due `to relative movement between the instrument and the target.

The particular nature of the invention as well as other objects and advantages thereof will appear most clearly from a description of a preferred embodiment as shown in the accompanying drawings in which Fig. l-is a diagrammatic perspective view of the instrument;

Fig. 2 is a view on an enlarged scale of the mechanism for applying torques to the angie gyroscope of Fig. 1 to cause it to precess as required.

Fig. 3 is a detailed view of a device used in connection with the angle gyroscope, and

Fig. 4 is a wiring diagram.

Referring to Fig. l, i represents the base of the instrument which is rotatably mounted upon a fixed pedestal which carries an annular rack 2 surrounding the base. For the purpose of training the instrument there is provided a pair of trainers hand wheels 3 which will be understood to be suitably mounted upon the base of the instrument.

These hand wheels are connected by a shaft 4 which through bevel gears 5. a shaft 6 and bevel gears 'i drives a shaft 8 having splined upon its free end a pair of uniiled gears 9 adapted to be shifted by a lever 9'. When in the position shown one of the gears engages a gear forming part of the side I0' of a differential designated generally as l0. The center I0" of the differential is attached to a shaft I l which through bevel gears I2 and shaft i3 drives a pinion I4 meshing with the training rack 2. The shaft i3 is mounted in a bracket attached to the base of the instrument. The third side Ill" of the differential is connected through gears l5 with a motor I6 controlled from the angle gyroscope of the instrument as will hereinafter be described. The shaft 8 drives through bevel gears l1 and shaft I8 an electrical generator i9 shown in Fig. 2 and the function of which will be hereinafter explained. The shaft il is provided with a pinion 20 adapted to be engaged by the other gear of the pair 9 when the shifting lever is operated. The pinion also drives a dial 2l readable against a pointer 22 for showing the bearing of the instrument. The shifting lever 9' is provided with a switch i6 in the circuit of the motor I6 as will more clearly appear when the circuits of the instrument are described in connection with Fig. 4. The switch consists of a ilxed contact element and a movable contact element attached to the lever.

The pointer of the instrument is furnished with a pair of hand wheels 23 suitably mounted upon the base of the instrument and connected by a shaft 24 which through bevel gears 25, shaft 26, and bevel gears 21 drives a shaft 28 having splined upon its free end a pair of unied gears 29 adapted to be shifted by a lever 29'. When in the position shown one of the gears engages a gear Iforming part of the side 38'01' 'a differential 39. The center 38" of the differential is attached to a shaft 3| extending through the side 38' and provided with a pinion 3| adapted to be engaged by the other gear of the pair 29 when the sluiting lever vis operated. The shaft 3| extends in the other direction through the instrument where it drives bevel gears 32, shaft 33, gear 34 and gear 34' attached to one side 35 of a differential 35, the other elements of which will be hereinafter described. The second side 38"' of the diierential 38\is-connected through gears 38 to a motor 31 controlled by the angie gyroscope as will hereinafter appear. The shifting lever 29 is provided with a switch 31' in the circuit of the motor 31 as will appear more clearly in connection with the description of Fig. 4, this switch being similar to switch i6' previously described.

As in the case of the training elements of the instrument, the shaft 28 is connected to bevel gears 38 and shaft 39 to a generator 48, the funcl tion of which will be hereinafter explained.

Similarly the shaft 3l is provided with a pinion 4| for driving a dial 42 reading against an index 43 to show the elevation of the instrument.

Rising from the base near its periphery is a standard 44 winch serves as a support for one end of a main frame 45 through a suitable bearing 46. Another standard 41 rises from a member 48 which will be understood as being attached to the base oi the instrument. The standard 41 serves as a second support through a bearing 49 for the main frame 45 which at this part of the instrument is formed with an arcuate portion 45' between the ends of which the angle gyroscope 92 is mounted as will hereinafter appear.

For the purpose of stabilizing the elements of the instrument there is provided a level gyroscope 58 consisting of a rotor and a case, the latter being provided with trunnions mounted within a girnbal ring 52 which in turn is mounted upon tubular trunnions 53 integral with opposite sides of the main frame 45 and lying at right angles to the trunnions 5|. A double bail frame 54 is mounted at its ends upon the trunnions 53 and consists of a horizontal portion 55 and a vertical depending portion 58. The portion 55 carries a vertically disposed gear sector` `51 meshing with a worm 58 on a shaft 59 mounted in a transverse member 88 ofthe main frame 48. The shaft is connected by pinions 8| to a shaft 62 also mounted in the transverse member 88 and connected at its lower end through a universal joint 83 to a shaft 84, the universal joint being on the line between the bearings 48 and 49 of the main frame so as to allow for the relative movement between the main frame and the parts carried thereby on the one hand and the parts movable with the base of the instrument on the other hand. The shaft 64 passes through a bearing 65 at the outer end of a bracket 6B extending from the standard 41.

The lower end of shaft 64 is connected by bevel gears 61 to a shaft 68 connected to a motor 89 controlled from a contact device associated with the level gyroscope 50. The device consists of a roller 1| attached to but insulated from the portion 55 of frame 54 and coacting with a pair oi contacts 12 insulated from each other and from the gimbai ring 52 on which they are mounted. As shown most clearly in Fig. 4 the roller is electrically connected to one main 13 of a source of current supply and the contacts are connected by conductors 14 to the reversely wound ileld windings 15 of the motor 89, the armature 18 of which is connected by a conductor 11 to the other main 18.

As shown in Fig 1 the shaft 88 is also connected through bevel gears 19 to a shaft 88 attached to the center 35" of the differential 38.

The other side 35"' of .the differential is con-- nected through gears 8|, shaft 82, and bevel gears 83 to a. shaft 84 passing through a bearing in a bracket 85 extending from the standard 41. The upper end of shaft 94 is connected to a universal joint 86 in line with the bearings 48 and 49 of the main frame. The universal joint is also connected to a shaft 81 passing through a bracket 88 forming part of the main frame. Through gears 89 the shaft drives a worm 98 meshing with a gear sector 9| forming part of the mounting of the angle gyroscope 92 as will presently be described.

The arcuate portion 45' of the main frame is provided on opposite sides of the bearing 49 with a pair of depending members 93 between the lower ends of which extends n. gear sector 94 meshing with a worm 95 on a shaft 96 connected to a motor 91 controlled by a contact device 98 associated with the levelgyroscope 58. This device is similar to the device 18 previously described and consists of a roller 99 carried at the end of a bracket |88 attached to but insulated from the case of the gyroscope. The roller coacts with a pair of contacts |8| insulated from each other and from a supporting bracket |82 extending upwardly from the portion of the gimbal ring 52 which serves as a bearing for one of the trunnions 5|. As shown in Fig. 4 the roller 99 is electrically connected to the main 13 and the contacts |8| are connected by conductors |83 to the reversely wound eld windings |84 of the motor 91, the armature |85 of which is connected to the conductor 11 leading to the otherv main 18.

The case of the angle gyroscope 92 is provided with trunnions |86 mounted within a gimbal ring |81 which in turn is mounted upon tubular trunnions |88 integral with the free ends of the arcuate portion 45' of the main frame. Also mounted upon the trunnions |88 is a triple bail frame |89 consisting of a portion ||8 to which the upper end of the gear sector 9| is attached, a portion to which the other end of the sector is attached and a portion ||2 shaped to conform generally to the contour of the case of the angle gyroscope and connected at its outermost portion with the portion ||8 by a part H3.

At its upper end the standard 41 carries a frame ||4 having at its upper end an annular member ||5 Within which is a circular plate H8. The annular member H8 has a cross bar I|1 which has a bearing at its center for a trunnion ||8 which is rigid with and projects from the upper side of the plate H8. Extending downwardly from the plate is a pair of side arms ||9 connected by a cross bar |28 mounted at its center upon a trunnion |2| attached to the bottom of the frame ||4. Below the cross bar the side arms ||9 extend outwardly and carry at their lower ends trunnions |22 which serve as supports for the ends of a bail |23 which at its outermost portion is enlarged (as shown most clearly in Fig. 3) and carries a pin |24 threaded therethrough. 'Ihe pin extends through a corresponding enlargement at the junction of the portions ||2 and ||3 of the frame |89 and has a pointed inner end extending within a recess in a plug |25 of suitable material. such as cork, embedded in a recess in a projecting portion of the case of the angle gyroscope.

Connected tothe bail |23 is a link |26 attached at its upper end to an arm |21 on a shaft- |28 mounted in a bearing in one of the side arms ||9 and in a bearing member |29 extending from the lower side of the plate H6. The shaft |28 also carries an arm |30 having a roller |3| at its free end. The roller bears against the lower edge of another arm |32 on a shaft |33 mounted in a bearing on the underside of the plate I6. The edge of the arm |32 is held against the roller |3| by a spring |34. The shaft |33 also carries an arm |35 to which is attached a link |36 extendingto a reflecting prism |31 mounted between the ends of arms |38 extending upwardly from a base |39 which is attached to the circular plate 6 by depending lugs |40 to provide space below the base for the cross bar ||1 and the end of trunnion I8.

Optically associated with the reilecting prism |31 is a pair of reflecting prisms |4| and |42. Optically associated with the reflecting prism |4| is a pair of lenses |43, a pentaprisrn |44, a lens |45 and a telescope |4'6 for the trainer of the instrument. Similarly associated with the prism |42 is a pair of lenses |41, a pentaprism |48, a lens |49 and a telescope |50 for the pointer of the instrument. It will be understood that all of the optical elements excepting the prism |31 are suitably mounted in fixed relation to the base of the instrument.

Associated with the angle gyroscope 92 is a contact device |6| consisting of a roller |52 on a bracket |53 attached to but insulated from the case of the gyroscope. The roller `coacts with a pair of contacts |54 insulated from each other and from a bracket |55 by which they are carried upon the gimbal ring |01 of the gyroscope. As shown most clearly in Fig. 4 the roller |52 is electrically connected to the main 13 and the contacts |54 are electrically connected to the reversely wound field windings |56 of the motor i6, the armature |51 of which is connected through the switch I6' associated with shifting device 9 to the conductor 11 leading to the main 18. These elements constitute the means by which the training motor I6 is controlled automatically from the angle gyroscope as will be more fully explained hereinafter.

A similar contact device |58 is provided for controlling the elevation motor 31 from the angle gyroscope. For thispurpose an arm |59 is attached to but insulated from the gimbal ring |01 and carries a roller |60 coacting with a pair of contacts |6| insulated from each other and mounted on but insulated from the portion ||2 of the frame |09. As shown in Fig. 4 the roller |60 is connected to the main 13 and the contacts |6| are connected to the reversely wound field windings |62 of the motor 31, the armature |63 of which is connected to the conductor 11 leading to the main 18, the circuit passing through the switch 31 associated with the shifting device 29'.

The angle gyroscope 92 is caused to precess to maintain its spinning axis directed at a target and thereby control the movements of the instrument. For the purpose of applying the torque which causes the gyroscope to precess in train there is mounted upon the standard 44 a crank |64 adapted to be set in accordance with the rate of change of bearing ot the target in the plane of the line of sight and a horizontal line perpendicular to the line of sight, as determined by suitable calculating mechanism forming no part of the invention. While as shown herein this quantity is adapted to be put into the instrument manually, it may be applied automatically by suitable means, such as the shaft 253 of my copending application referred to above, by adding to the present device thelcalculating mechanism of that application. The crank is provided with a pinion |65 for driving a dial |66 reading against a pointer |61 to show when the correct value of the quantity has been applied by the crank.

` The crank is connected through bevel gears |68 to a shaft |69 mounted in a Ibracket extending from the top of the standard 44. As shown most clearly in Fig. 2 the lower portion of the shaft is screw-threaded through a lug |10 projecting from a carriage |1| movably mounted, as by means of rollers |12, within a' channel |13 in one side of the standard. Pivotally mounted on the carriage is a lever |14 halving a substantially vertical arm |15 and an arm |16 inclined to the former arm. A tension spring |11 is connected at its lower end to the free end of am |16 and at its upper end to a rod |18 mounted in .fbrackets |19 extending from the carriage |1|. The top of the rod is screw-threaded and carries a nut by which the tension of the spring may be adjusted. The carriage is also provided with an index mark |8| reading against a scale |82 on the standard 44.

Pivotally attached to the upper end of the vertical arm |15 is a forked member |83 carrying a pair of rollers |84 which are pressed by the spring |11 against a rod |85 pivoted at |86 to the standard 44. The lower end of the rod |85 carries a coil |81 electrically connected by conductors |88 with the armature |89 of generator I9, the iield |90 of which is connected by conductors |9| to the mains 13 and 18. The coil |81 surrounds a pole piece |92 of an electro-magnet |93 having its coil |94 connected to the mains 13 and 18 by conductors |95 and its other pole piece |96 shaped to terminate near the bottom of the coil |81.

The top of the rod |85 is connected by a strap |91 to an arm |98 pivoted at its lower end upon the extension 66 of the standard 41. 'I'he arm |98 passes through the forked end of an arm |99 .pivoted at 200 in one of the side members of the main frame 45. The other end of the arm engages a rod 20| passing through the hollow trunnion |08 and engaging an arm 202 on a shaft 203 suitably mounted in the portion of the triplebail frame of the angle gyroscope. The other end of the shaft carries an arm 204 which is connected by a wire 205 to the gimbal ring |01 at a point near the lower trunnion |06. The girnbal ring is also provided with an arm 206 to which is connected one end of a spring 201, the other end of which is connected to an arm 208 attached to the portion ||0 of the triple-bail frame.

The scale |82 reads in opposite directions from a zero point and the parts are so proportioned that when the index mark |8| on carriage |1| coincides with the zero point, the forces applied to the angle gyroscope lby the spring |11 acting through the lever |14, rod |84, strap |91, arms |98 and |99, rod 20|, arms 202 and 204 and wire 205 is exactly balanced by the force exerted by the spring 201 connected lbetween the triple-bail frame |09 and the gimbal ring |01 to which the 'Wire 205 is connected, so that under these conditions no torque is applied to the angle gyrosco'pe about its trunnion axis |08| 08.

.Similar mechanism is provided for applying a torqueto the angle gyroscope to cause it to pre- 7 A cess in elevation. This mechanism consists of a crank 209 adapted to be set in accordance with the rate of change of elevation of the target as determined by suitable devices. As inthe case of the corresponding train element |64, the elevation element may be set automatically by a member, such as a shaft 313 oi my copending application referred to above. The crank 203 is connected .by a pinion 2|0 with a dial 21| readable against an index 2|2 to show the value Put into the instrument. The crank is connected by bevel gears 2|3 to a shaft 2|4 mounted in a bracket at the top of the standard 44 and, as shown most clearly in Fig. 2; is provided with a screw-threaded portion extending through a lug v of connection that the torque applied to the gyro 2|5 Iprojecting from a carriage 2|6 similar to the carriage |1| and mounted by rollers in the opposite side of the standard 44. The carriage bears an index mark 2|1 reading against a scale 2|1' on the standard.

The carriage 2|6 carries a lever 2|8 having a vertical arm 2 I 9 and an arm 220 inclined thereto. The free end of the arm is connected to a spring 22| attached to a. rod 222 passing through brackets 223 projecting from the carriage 2|6 and provided at its upper end with an adjusting nut 224. The upper end of the vertical arm 2|-6 carries a pair of rollers 225 engaging a rod 226 pivoted at 221 to the standard 44 and carrying at its lower end a coil 228 connected by conductors 229 to the armature 230 of the generator 40, the ileld 23| of which is connected to the conductors 19| leading to the mains 13 and 18. The coil 228 surrounds one pole piece'232 of an electro-magnet 233, the coil 234 of which is permanently connected to the mains 13 and 18. The other pole piece 235 is shaped to lie near the bottom ot the coil 228.

The upper end of the rod 226 is connected by a 'strap 236 to an arm 231 pivoted on the Ibracket 66 of the standard 41 and passing through the forked end of an arm 238 pivoted at 239 in the other side member of the main frame 45. The other end of the arm engages a rod 240 movably mounted in the hollow trunnion |08 and engaging the end of a crank 24| pivoted upon the portion of the triple-bail frame and connected at its other end to a wire 242 attached to the case of the angle gyroscope 92. The gimbal ring |01 carries a bracket 243 connected by a spring 244 to a bracket 245 attached to the case of the gyroscope.

As in the case of the mechanism for precessing the angle gyroscope in train, the parts just described are so proportioned that Iwhen the index mark 2|1 of the carriage 2|6 coincides with the zero point of the corresponding scale 2|1' the force applied to the angle gyroscope by the spring 22| through lever 2|8, rod 226, strap 236, arms 231 and 238, rod 240, crank 24| and wire 242 is exactly balanced by the force exerted by the spring 244 connected between the girrnbal ring |01 and the case of the angle gyroscope to whichthe wire 242 is also attached, so that under these conditions no torque is applied to the gyroscope about the trunnion axis "i6-|06.

The arms |16 and 220 of levers |14 and 2|6 respectively are so inclined with respect to the springs |11 and 22| of the levers that any changes of position of the rods |85 and 226 are not accompanied by any chagnes of pressure of the rollers |64 and 225 respectively and therefore no changes in the torques applied to the angle gyroscope by these elements. The forces exerted by the springs upon the rods would normally vary remains substantially constant.

As gyroscopes are subject to straying or Wandering from their vtrue positions provision is made in the instrumentfor compensating for such straying as otherwise errors in the positioning of the elements of the apparatus which depend upon the level gyroscope 50 would be introduced. For the purpose of detecting such straying the top of the case of the gyroscope carries a spirit level 246 in which departure of the bubble from its normal position indicates straying of the gyroscope.

Invgeneral, compensation for straying is produced by precessing the gyroscope back to its normal position by the application of a torque of the requiredanagnitude about one or both of its axes. For this purpose there is provided a r handle 241 centralized by a spring 248 and attached to a rod 249 mounted in suitable bearings and provided with an arm 250 having a forked extremity which engages the lower end of a lever 25| pivotally mounted at 252 on the bracket 66 of the standard 41. The upper end of the lever is connected by a spring 253 to a member 254 attached to the upper portion of the standard 41. At an intermediate point the lever 5| engages a lever 255 pivotally mounted at 256 upon one of the side members of the main frame 45. The other end of this lever engages a rod 251 slidably `rn-ounted in the corresponding hollow trunnion 53. The inner end of the rod engages the upper end of an arm 258 attached to a shaft 259 mounted in a bearing in the portion 56 of the double-bail frame 54. A spring 260 is connected -between the arm and the portion of the frame just referred to. An arm 26| is attached to the other end of the shaft 259 and has attached to its free end a strap 262 terminating in an eye surrounding but normally out of contact with a pin 263 projecting inwardly from the gimbal ring 52 below the corresponding trunnion 5|.

A substantially similar arrangement is provided for applying a torque about the other axis of the level gyroscope. This consists of a handle 264 provided with a centralizing spring 265 and attached to a rod 266 mounted in suitable bearings and having an arm 261, the forked end of which engages the lower end of a lever 268 pivotally mounted at 269 upon the bracket 66 and connected at its upper end by a spring 210 to the member 254. At an intermediate point the lever 268 engages a lever 21| pivoted at 212 upon one of the side members of the main frame 45. The other end of the lever engages a rod 213 slidably mounted in one of the hollow trunnions 53. The inner end of the rod engages the upper end of a lever 214 pivotally mounted on the portion 56 of the double-bail frame and connected to this portion by a spring 215. Attached to the other end of the lever is a strap 216 terminating in an eye which loosely surrounds a pin 211 projecting from the case of the level gyroscope.

In the operation of the instrument the target to which it is to be directed is firstu picked up by the trainer and pointer by slewing operations. To accomplish this the levers 9 and 29' are shifted from the positions shown inthe drawing to their alternative positions in which the larger gears of the pairs 9 and 29 are in engagement with the pinions 20 and 3|' respectively on shafts and 3|. At the same time the circuits of the motors I6 and 31 are broken at the switches I6' and 31' respectively.

There is thus established a direct drive from the trainers hand wheels 3 through shaft 4, bevel gears 5, shaft 6, bevel gears 1, shaft 8, larger gear 9, pinion 20, shaft |I, bevel gears I2, shaft I3 and pinion I4 whereby the instrument may be rapidly trained until the image of the target produced by the reflecting prisms |31 and |4|, the lenses |43, the pentaprism'l44, the lens |45 and the lenses of the trainers telescope |46 is brought into its eld of view provided the pointer who is simultaneously operating the elements under his control has suitably adjusted the prism |31 as will now be described 'I'he pointer by manipulation of his hand wheels 23 will drive shaft 24, bevel gears 25, shaft 26, bevel gears 21, shaft 29, larger gear 29, pinion 3|', shaft 8|, bevel gears 32, shaft 33, gears 34 and 34' and theside 35 of the differential 35. Regarding the center 35" of the differential as fixed since it is connected by shaft 80, bevel gears 19 and shaft 60 to the moto'r 69, the other side 35"' will be actuated to drive through gears 8|, shaft 82, bevel gears 83, shaft 94, universal joint 86, shaft 81 and gears 89, the worm 90 to turn the gear sector 9| and the triple bail frame |09 to which it is connected. 'I'hrough the pin |24 fitting within the recess in the end of the case of the angle gyroscope, the latter will vbe caused to follow the movement of the triple-bail frame within which it is mounted in accordance with the principles of gyroscopic action. Through the pin |24 the bail |23 will also be correspondingly turned and through link |26, arm |21 and shaft |28 turn the `arm |30. the end of this arm is held in contact with arm |32 by spring |34 the latter arm will also be turned, but only through one-half the angle through which the arm |30 is turned, since the latter is one-half the length of the arm |32. The movement imparted to arm |32 will through shaft |33, arm |35 and link |36 betransmitted to the reflecting prim |31 to turn it through onehalf the angle of elevation ofthe target so that the image of the target is brought into the field of view of the pointers telescope |50, this image being formed by the reflecting prisms |31 and |42, the lenses |41, the pentaprism |48, the lens |49 and the lenses of the telescope. It will be understood that the simultaneous operation of the instrument by the trainer will bring the imagelnto the iield of view of the pointers telescope insofar as train is concerned.

Since the roller |3| at As a result of the coacting slewing operations I from having any effect upon the diierentials 10 I0 and 30 due to possible establishing oi' their control circuits through the contact devices associated with the angle gyroscope.

It will be understood that even during the preliminary setting f the instrument the level gyroscope 50 is in operation and, except for straying, maintains its plane of rotation fixed in space.

Due, however, to the cross roll of the craft there will be relative movement between the gyroscope and the gimbal ring 52 about the trunnions 5|. There will therefore be relative movement between the roller 99 and the contacts |0| to establish a. circuit from the main 13 through one or the other of the conductors |03, according to the direction of the relative movement, and the corresponding field winding |04 of the motor 91 from which the circuit continues through armature |05 and conductor 11to the other main 18. 'I'he energization of the motor will through shaft 96, worm and gear sector 94 turn the main frame 45 and the gimbal ring 52 until the contacts |0| occupy their normal position with respect to the roller 99, that is, with the roller upon the insulation between the contacts. The elements thus constitute a, follow-up system by which the main frame 45 by a series of steps as described above is maintained in a horizontal plane about its' bearings 46 and 49.

The relative movement between the main frame 45 and the elements which move with the craft changes the relation between the ends of the arcuate portion 45 of the frame and the adjacent lower ends of the side arms I9. Due to the connection from the trunnions |08 at these ends of the main frame through the triple-bail frame |09, pin |24 and bail |23 to which the lower ends ofv the side arms ||9 are connected, there is a readjustment of these parts whereby the side arms are turned about the inclined axis through the trunnions ||8 and |2| to cause the circular plate H6 to be correspondingly turned. As this plate turns it also turns the arms |38 between which the prism |31 is mounted so as to turn the prism suciently to compensate for the effect of cross roll upon the images of the target in the fields of view of the trainers and pointers telescopes |46 and |50 respectively. In other words, the fields ofl view of these telescopes are stabilized against the eect of cross roll by compensating relative movement between the prism |31 and the remaining optical elements which partake of the cross roll of the craft.

As a result of roll of the craft there will be relative movement between the double-bail frame 54 and the gimbal ring 52 within which the level gyroscope is mounted. There will therefore be relative movement between the roller 1I and the contacts 12 to establish a, circuit from the main 13 through one or the other of the conductors 14, according to the direction of the relative movement, and the corresponding eld winding 15 of the motor 69 from which the circuit continues through armature 16 and conductor 11 to the other main 18. The energization of the motor 69 will through shaft 68, bevel gears 61, shaft 64, universal joint 63, shaft 62, gears 6l, shaft 59, worm 58 and gear sector 51 turn the double-bail frame, 54 until the roller 1| occupies its normal position upon the insulation between the contacts 12. 'I'he elements thus constitute a follow-up system by which the double bail frame 54 by a series of steps as described above is maintained in its normal relation to the level gyroscope 50.

The motor 69 through its shaft 68, bevel gears 19 and shaft 80 correspondingly drives thevcenter 86" of the differential 86. RegardingA the side 86' as xed the second side 86" will be turned vand through the gears 8|, shaft 82, bevel gears 83. shaft 84, universal Joint 86, shaft 81. gears 69, worm 90 and gear sector 9| maintain the triple-bail frame |09 stabilizedV irrespective of the roll of the craft. The operation above described maintains the elements such as the triplebail frame |09 and the bail |23 stabilized. Since the bail |23 controls the position of the prism |31 the latter will be maintained in a position to keep the target in the field of view of the telescopes irrespective of movement of the optical elements which move with the craft.

After the instrument has been directed at the target by the preliminary slewing operation, the estimated rate of change of bearing of the target in the plane of the line of sight and a horizontal line perpendicular to the line of sight is put into the instrument by the crank |64, the dial |66 showing when the desired value has been applied. The crank will be turned in one direction or the other according to the direction of the target with respect to the instrument. Through the bevel gears |68 and shaft |69, the carriage |1| will be displaced to a corresponding position and there will be a corresponding displacement of the rollers |84 on the rod |85. Assuming that the carriage is displaced downward- 1y from the position shown in Fig. 2, there will be a corresponding increase of the effective lever arm between the pivot |86 and the point at which the spring |11 applies its force to the rod |85 through the lever |14 and rollers |84. The increased force due to the increased lever arm will be transmitted through the strap |91, arms |98 and |99, rod 20|, arm 202, shaft 203, arm 204 and wire 205 to the angle gyroscope 92 where it will overcome the opposing force exerted by the spring 201 to apply a torque to the gyroscope about the trunnion axis |08|08 to cause the Agyroscope to precess about its trunnion axis |06|06 in the direction to follow the target.

Conversely if the carriage |1| be displaced upwardly from the position shown in Fig. 2 the effective lever arm of the rod |85 between the pivot |86 and the rollers |84 will be lessened so that the spring 201 associated with the angle gyroscope will overbalance the effect of the spring |11 applied through the strap |91 and the connected elements as previously described to cause ring |01 to establish a circuit from the main 'I3v through the roller and contact with which it is inengagement and the corresponding eld winding |56 of the motor 6 from which the circuit will continue through the armature |51 of the motor. the switch |6 which is in a closed position and the conductor 11 to the other main 18.

The resultant energization of the motor I6 will through gears I5 turn the side |0"' of the differential I0 and regarding its lother side I0' as fixed since it is connected to the trainers hand wheels 3 which at this time are assumed to be xed. the center I0" of the differential will be turned and through the shaft bevel gears l2 l2 and shaft I3, the pinion I4 will turn the base of the instrument within the rack 2 to cause-the instrument to be automatically driven in accordance with the estimated movement of the tlerget as put into the instrument by the crank In practice. however, the estimated rate of change of bearing of the target as set into the instrument may differ from its true rate. Such difference will be manifest to the trainer by a departure of the target from the vertical cross wire of his telescope. Upon noticing such a deviation he will manipulate his hand wheels 3 to restore the target to the cross wire. This is accomplished through the shaft 4, bevel gears 5, shaft 6, bevel gears 1, shaft 0, gear 8. side |0' of the differential l0, center I0" of the differential (regarding the second side |0'" as fixed) shaft bevel gears |2, shaft I3 and pinion |4 to produce a slight manual training of the instrument to correct for the deviation of the target. At the same time, the shaft 8 will through bevel gears |1 and shaft i8 drive the armature |89 of the generator I9. the field |90 of which is permanently energized from the mains 13 and 18 over conductors |9I.

The current generated by the movement of the armature will energize the coil |81 with a polarity depending upon the direction of rotation of the armature of the generator which in turn depends upon the direction in which the trainers hand wheels are turned to restore the target to the cross wire of his telescope. The energization of the coil |81 will result in a. repulsion or attraction of the coil by the poles |92 and |96 of the permanently energized electro-magnet |93 so that there will be a corresponding displacement of the rod |85 to which the coil is attached. This will either increase or decrease the force applied to the angle gyroscope through the strap |91 and connected elements as previously described according to the direction of movement of the coil |81. There will, therefore be a corresponding change in the torque applied to the angle gyroscope to alter its rate of precession and this change will be accompanied by a. corresponding change in the rate at which the instrument is automatically trained under the control of the angle gyroscope. In order that the changes in torque shall produce corresponding changes in the precession of the gyroscope the speed of its rotor should be maintained as nearly constant as possible.

In order. however, that the instrument may be maintained in corrected condition after the operations described above have been performed it is necessary to make a correctional adjustment by the crank |64 to slightly alter the position of the carriage |1| and therefore change the torque applied to the angle gyroscope to cause it to continue to precess at the correct rate to maintain the vertical cross Wires of the trainers and pointer's telescopes on the target.

Simultaneously with the automatic operation of the instrument in train there will be a similar operation in elevation. To produce this the crank 209 is adjusted in accordance with the estimated rate of change of elevation of the target. the value of this quantity being shown by the dial 2|| geared to the crank. Through bevel gears 2|3 and shaft 2|4 carriage 2|6 will be displaced from its zero position in one direction or the other according to Whether the elevation of the target is increasing or decreasing. As in the CaSe 0f the training elements, displacement of the carriage downwardly from the position shown v in Fig. 2 will increase the effective lever arm between pivct 221 and rollers 225 to cause a force to be applied through strap 236, arms 231 and 238, rod 240, lever 24|, and wire 242 to the angle gyroscope 92 about the trunnion axis |06|06 to overbalance the force applied about this same aXiS by the Spring 244 connected between the gyroscope and the gimbal ring |01. The torque thus applied to the gyroscope will cause it to precess about its trunnion axis |08-.l08 in the required direction to :followv the target.

Also as in the case o! the training elements, a displacement of the carriage 2|6 upwardly from the position shown in Fig. 2 will cause a decrease in the force applied to the' angle gyroscope through the strap 236 and connected elements as described above so that the spring 244 will predominate-in applying a torque to the gyroscope about the trunnion axis |06-I06 to cause it to precess about the other trunnion axis |08| 08 in the opposite direction.

InY either case the precessional movement of the gyroscope will carry with it the gimbal ring |01 and there will be relative movement between the roller |60 carried thereby and the contacts I 6| mounted on the surrounding triple-bail frame |09. A circuit will therefore be established from the main 13 through one or the other of the field windings |62 `of the motor 31 according to the direction of precession of the gyroscope. The circuit will continue through thev armature |63 of the motor, the now closed switch 31' and conductor 11 to the other main 18.

The energization of the motor 31 will through gears 36 drive the side 30"' of diii'erential 30 and regarding its other side 30' as fixed since it-is connected to the pointers hand wheels 23, the center 30" will be turned to drive the shaft 3| to which it is attached. 'I'he movement imparted to this shaft will be transmitted through bevel gears 32, shaft 33, gears 34, and 34' to the side 35 of the differential 35. Regarding its center 35" as fixed since it'is connected through shaft 80, bevel gears 19 and shaft 68 to the motor 69, the second side 3'5"' will be turned to drive through gears 8|, shaft 82, bevel gears 83, shaft 84, universal joint 86, shaft 81, gears 89 and Worm, 90, the gear sector 9| and the triple-bail frame |09 to which it is connected, The elements above described thusv constitute a followup system by which the frame will be automatically maintained in its normal relation to the angle gyroscope as the latter processes.

The motion imparted to the triple-bail frame will be transmitted through pin |24 to the bail |23 and thence through the link |26, arms |21, |30, |32, |35 and link |36 to the prism |31 to alter its position in accordance with the changing elevation of the target to maintain the latter in the field of view of the trafners and pointers telescopes provided the instrument has been accurately adj usted.

In practice, however, a correction of the estimated rate `of change of elevation of the target is usually required. This is made by the pointer who observing a deviation ofthe target from the horizontal cross wire of his telescope manipulates his hand wheels 23 to turn the side 30 Vof the differential 30 through shaft 24, bevel gears 25, shaft 2B, bevel gears 21, shaft 28 and gear 29. Regarding the second side 30" as fixed since it is connected to the motor 31, the center 30" will be turned to drive the shaft 3|, bevel gears y32, shaft 33, gears 34 and 34', sides 35 and 35"' of the differential 35, (regarding its center 35" as iixed) gears 8|, shaft 82, bevel gears 83, shaft 84, universal Joint 86, shaft 81, gears 89, Worm 90 and gear sector 8| to alter the position of the triple-bail frame |09 Aand therefore the bail |23 connected thereto by the pin |24. The correcting movement thus imparted to the'bail |23 will be transmitted through the links and arms previously described to the prism |31 to change it sufficiently to restore the horizontal cross wires of the telescopes t-o the target.

While a correctional movement is being imparted t the prism the armature 230 of the generator 40, shown in Fig. 2, will be rotated from shaft 28 through bevel gears 38 and shaft 39.

-- Since the 'field 23| of this generator is permanently energized from the mains 13 and 18 currentV will be supplied to the coil 228 attached to the end of rod 226 over conductors 229. This coil functions in the manner already described in connection with coil |81 and through strap 236 and the connected elements applies a correctional torque to the angle gy-roscope to cause it to precess about its trunnion axts |08|08 as the triple-bail frame is manually moved by the pointer so that the gyroscope and framemaintain their normal relation to each other while the correctional adjustment is being made in the position of the prism |31. Any deviation between thev gyroscope and the frame during this operation causes the motor 31 to be energized by the resulting relative movement between the roller |60 and contacts |6|. The motor acting through the differential 30 superimposes upon the movement being imparted to shaft 3| and the triple-bail frame |09 by the pointer a correctional movement to cause the frame to follow the movement of the gyroscope.

As in the case of training corrections, it is necessary to alter the rate of change of elevation as originally set up in the instrument by suitable manipulation of the crank 209 in order that the target may be accurately followed by the instrument.

It will be understood that throughout the operation -of the instrument the level gyroscope 50 is continually functioning in the manner already described to compensate for the effect upon the instrument of roll and cross roll of the craft While the angle gyroscope is controlling the instrument to automatically maintain the lines of sight of its telescopes upon the target in both train and elevation.

Reference has Ipreviously been made to the fact that the level gyroscope is subject to straying which is manifest by the departure of the bubble of the spirit level 246 from its normal position.` Such straying may be about either of its trunn ion axes alone or a combined movement about both of these axes. If the straying be about the trunnion axis 5I-5| an operator manipulates the handle 241 which through rod 249, arm 250 and lever 25| swings the lever 255 to alter the position of the rod 251 to actuate the arm 258 and the arm 26| connected thereto by the shaft 259 until the eye at the end of strap 262 engages pin 263, the eye being normally out of engagement with the pin so as not to interfere with the slight relative movement between the gyroscopeand its gimbal ring 52 which occurs as the gyroscope is performing its stabilizing function. By further movement of the handle 241 a torque may be applied to the gyroscope about its trunnion axis 53-53 of suflicientmagnitude to cause the gyroscope to precess about its trunnion axis 5|-5I until the bubble of the spirit level occupies its normal position, after which the elements of the precessing mechanism are restored to their normal positions by the centralizing spring 248 when the handle 241 is released.

When the level gyroscope strays about its trunnion axis 53-53 the handle 264 is manipulated to turn the rod 266, arm 261 and levers 268 and 21| to dispiace the rod 213 and the lever 214 until the eye at the upper end of the strap 218 engages the pin 211 projecting from the case of the gyroscope. By further movement of the handle 264 a torque may be applied about the trunnion axis I-5l to cause precession about the trunnion axis 53-53 until the bubble of the spirit level occupies its normal position showing that compensation has been made for straying of the gyroscope. The centralizing spring 265 restores the handle to normal position after it has been suitably actuated to correct for the straying of the gyroscope.

It will be understood that in practice all ofthe automatic operations hereinbefore described in seouence occur simultaneously while the correcting operations are performed manually from time to time or continuously as required, so that the sighting elements of the instrument are maintained in a predetermined relation to a line to the target irrespective of roll and cross roll of the craft when the correct rates of change of bearing and change ofelevation have been set up in the instrument,` the operators being only required to make the necessary adjustments to correct for changes in the motion of the target.

While a preferred embodiment of the invention has been shown and described it will be understood that it may be embodied in other forms and that various changes in structural details may be made without departing from its principle as defined in the appended claims.

I claim:

1. In a fire control instrument, the combination of a gyroscope, means settable to be selfacting to apply torques about mutually perpendicular axes of said gyroscope to precess the same in train and elevation, directional mechanism, and independently operable connections between said gyroscope and mechanism controlled by the former to automatically direct said mechanism in train and elevation.

2. In a re control instrument, the combination of a gyroscope, means settable to be self-acting to apply torques about mutually perpendicular axes of said gyroscope to precess the same in train and elevation, directional mechanism, means to direct said mechanism in train and elevation, and electric controls for said directing means governed by said gyroscope.

3. In a fire control instrument, the combination of a gyroscope, torque-applying means settable to be self-acting to precess said gyroscope in train and elevation, directional mechanism, means operable under the control of said gyroscope to direct said mechanism in train and elevation at a target, and auxiliary force-applying means operable to act on said torque-applying means as set to modify the torques applied thereby to said gyroscope in accordance with changes in the relative motion between the instrument and the target.

4. In a fire control instrument, the combination of a gyroscope, torque-applying means settable in accordance with estimated rates of movement of a target in train and elevation to precess said gyroscope in correspondence therewith. direc- 16 tional mechanism directed in train and elevation by said gyroscope, force-generating means operable proportionately to thediiferences in the estimated and true rates of movement of the target. and torce-applying means responsive thereto to act on said torque-applying means as set.

5. In a fire, control instrument, the combination of adjustable optical means provided with means to separately observe the relative angles between two relatively movable objects in train and elevation, a gyroscope. controlling means therefor settable inaccordance with estimated rates to automatically precess said gyroscope in train and elevation, means responsive to said gyroscope to direct said observing means to follow the movements of one of said objects in train and elevation, and correcting means actuated in accordance with separate indications of said observing means and acting on said controlling means to modify the precessional action thereof in accordance with differences between the observed relative movements and the automatic movements.

6. In a fire control instrument, a gyroscope, torque-applying means settable to precess said gyroscope in train and elevation, an adjustably mounted device, and controlling means therefor electrically governed by said gyroscope to automatically maintain said device in predetermined relation to a line of sight between two relatively moving objects irrespective of their relative movements in train and elevation.

7. In a lire control instrument, the combination of a gyroscope, an adjustable optical device for viewing a movable object, separate mounting means for said gyroscope and said device mounting the latter independently of said gyroscope, means controlling said gyroscope to cause it to generate the angular relation between the device and the object, and operating means between said gyroscope and device controlled by said gyroscope to adjust said device and maintain the latter at the generated angular position.

8. In a fire control instrument, the combination of a sighting device, a gyroscope controlling said device, precessing means for said gyroscope adjustable to cause the latter to control said device to automatically direct the line of sight of the device upon a target. and stabilizing mechanism co-operative with said gyroscopic control to maintain the line of sight upon the target irrespective of angular movement of the craft on which the instrument is mounted.

9. In a re control instrument, the combination of a sighting device, force-applying means subject to regulation in accordance with movements of a target, an intermediary control between said force-applying means and sighting device governed by the former and controlling the latter, and partially stabilized means operable in response to roll and cross roll of the craft on which the instrument is mounted and co-acting with said intermediary control to automatically maintain the line of sight oi the device upon a target.

10. In a re control instrument, the combination of a sighting device, force-applying means subject to regulation in accordance with movements of a target, an intermediary control between said force-applying -means and sighting device governed by the former and controlling the latter, partially stabilized means operable in response to roll and cross roll of the craft on which the instrument is mounted and co-acting with said intermediary control to automatically maintain the line of sight of the device upon a target, and adjusting' means operable to modify the force of said force-applying means to correct for changes in the relative motion between the craft and the target.

11. In a re control instrument, the combination of displaceable means. a directing device therefor, a governing control for said device, a mounting for the device susceptible to displacement in accordance with the roll and cross roll of a craft upon which the instrument is mounted, a gyroscope, means controlled by relative movement of `said mounting and gyroscope operable to act on said' directing device to compensate for the effect thereon oi such roll and cross roll, and means for correcting strayingof the gyroscope.

l2. In a re control instrument, the combination of a sighting device movable in elevation and train, controlling means comprising stabilized elements, displaceable elements co-acting with the rst named elements and movable relatively thereto in accordance with the roll and cross roll of the craft on which the instrument is mounted, and adjustable members controlled by said stabilized and displaceable elements to maintain a stable plane of reference from which the move- 'ments in elevation of the sighting device may be determined, and means including an azimuth reference point to serve as a datum from which the movements in train of the device may be determined. Y,

13. In a r-e control instrument, the combination of a directing device, adjustable precessing means, a gyroscope governed thereby to maintain the directing line of the device upon a target, and automatic means to compensate for the effect upon the directing device of motion of the craft upon which the instrument is mounted about mutually perpendicular horizontal axes, said compensating means including a stabilizing 'device and electrical controls governed by the stabilizing device and .the motion of the craft.

14. In a lire control instrument, the combination of a support, an optical element movably mounted on the support for viewing a target, a frame plvotally mounted on the support about an axis substantially parallel to the horizontal com-l ponent of the line of sight of the element, a gyroscope supported within the frame upon an axis parallel to the axis of the frame and upon an .axis perpendicular to said axis that is parallel to the axis of the frame, a power driven vfollowup mechanism forrmaintaining the frame in predetermined relation to the gyroscope with respect to the axis of the frame, a. second power driven follow-up mechanism for maintaining the optical element in predetermined relation to thegyroscope with respect to the axis perpendicular to the axis of the frame, means rendered active by straying of the gyroscope to indicate such straying and means for compensating for such straying of the gyroscope about its axes.

15. In a nre control instrument adapted to be mounted on a rockable craft, the combination of a member mounted to be directed in train and elevation, a directing device therefor displaceable in train and elevation, operating means operable in accordance with rates of train and elevation controlling said device, a stabilizing gyroscope, a plurality of pivoted frames some of which 70 universally support said gyroscope about mutually perpendicular axes, electrical contact devices having co-acting contacts respectively stabilized by said gyroscope and movable by said frames in response to roll and cross roll of the craft upon 18 which the instru-ment is mounted, and adjusting means controlled by said contact devices to modify the operation of said directing device and directed member to compensate for the effect thereupon of the roll and cross'roll of the craft.

16. In a fire control instrument, the combination of a support, a frame plvotally mounted -upon said support for movement about an axis, stabilizing means governing said frame to stabilize the same about its said axis, a rigid angularly displaceable structure mounted on said support for movement about an inclined axis, an optical element plvotally mounted on said structure about an axis perpendicular to said inclined axis, a directing device universally mounted on said frame, connections between said directing device and angularly displaceable structure for turning the latter upon relative movement between said support and said frame, and connections between said directing device and said optical element for turning the latter about its axis in predetermined relation to the relative movement between said directing device and said frame.

17. In a iire control instrument, the combination of a support, a frame plvotally mounted upon said support for movement about an axis, stabilizing means governing said frame to stabilize the same about its said axis, a rigid angularly displaceable structure mounted on said support for movement about an inclined axis, an optical element plvotally mounted on said support about an axis perpendicular to said inclined axis, a directing device mounted on said frame for movement in elevation with respect to said frame, operating connections between said stabilizing means and said directing device, actuating means controlling said directing device to move the same in accordance with the movement in elevation of a target, connections between said directing device and said rigid angularly displaceable structure for turning the latter upon relative movement between said support and said frame, and connections between said directing device and said optical element lor turning 'said element about its axis in predetermined relation to the relative movement between said directing device and said frame and/or the movement in elevation of the target.

18. In a fire control instrument, the combination of directional mechanism, a gyroscope, electrically controlled means governed by said gyroscope to operate said mechanism, and torque-applying means settable in accordance with the rate of change of position of a target in a given direction to be self-acting to precess said gyroscope whereby the latter actuates said electrically controlled means to direct said mechanism at the target.

19. In a ilre control instrument, the combination of directional mechanism, a gyroscope controlling said mechanism, members relatively displaceable in accordance with the estimated rate of ch-ange oi. position of a target in a given direction, co-acting levers plvotally mounted on the respective members the pivot of each lever being fixedly located with respect to the member mounting the lever, force-applying means acting on one of said levers, torque-applying connections from the other lever to said gyroscope for precessing the same to direct said mechanism at the target, and adjusting means operable according to the true rate of change of position of the target to adjust the torque-applying means in accordance with diiierences between the estimated and true rates of change of position.

20. In a re control instrument, the combination of a universally mounted gyroscpe,' torqueapplying means settable in accordance with the estimated rates of change of bearing and elevation of a target to precess said gyroscope about mutually perpendicular axes. positioning means responsive to the precession of the syroscope about said axes, a sighting device actuated by said positioning means to follow a target in train and elevation and being provided with observing portions respectively indicating in train and in elevation the following movement of the sighting device with respect to the true movement of the target, and adjusting means energizable to coact with said torque-applying means to adjust the latter in accordance with differences between the estimated and true rates of change oibearing and elevation to cause the line of sight of said sighting device to accurately follow the target.

21. In a ilre control instrument, the combination of a support subject to angular movements about mutually perpendicular axes, optical elements rigid with said support to partake of angular movements of the latter about said -mutually perpendicular axes, an adjustable optical element mounted in co-operative relation to the first named loptical elements for movement independently thereof about axes of train and elevation, a stabilizing device, operatingfconnections between said device and said adjustable optical element controlled by the former to move the latter to compensate for relative movements between the stabilizing device and the support about the iirst named axes, and controlling mechanism operable to direct said adjustable optical element about axes oi' train and elevation independently of said other optical elements.

22. In a lire control instrument for use on a craft subject to oscillatory movement, the combination of a sighting device having optical el'ements partaking of the movement of the craft, a co-operating optical element mounted for movement about mutually perpendicular axes, a pivotally mounted gyroscope, connections automatically operable by said gyroscope to move said co-v bilizing means to direct saiddirectional mechanism at the target, and adjusting means co-acting with said rate control 'mechanism to modify the action thereof in accord-ance with changes in the relative motion between the instrument and the target. O

25. In a re control instrument, the combination of a support, a sighting device mounted on said support for movement in train therewith and for movement in elevation with respect to the support, means for imparting to the support a slewing movement in train, variable speed mechanism settable to be self-acting comprising force-applying means and actuating mechanism automatically responsive to force applied by said means to move said support and sighting device in train, adjusting -means to set said force-applying means to cause said actuating mechanism to automatically move said support and sighting device in accordance with the rate of movement of the target in train, means for imparting to the -sighting device a slewing movement in elevation, another variable speed mechanism settable to be self-acting comprising other force-applying -means co-acting with said actuating mechanism, the latter being also automatically responsive to force applied by said second force-applying means to move said sighting device in elevation,

operating optical element about said axes to compensate for the effect upon said sighting device oi' the roll and cross roll of the craft, an indicator actuated by said gyroscope to indicate straying thereof. precessional means operable to act on said gyroscope to compensate for its straying,

and actuating means for said co-operating optical element to move the latter about its said axes to follow a target in train and elevation.

23. In a fire control instrument subject to oscillatory movement, the combination of directional mechanism, stabilizing means partially controlling the same to compensate for the effect upon the mechanism o! angular movement of the craft on which the instrument is mounted, and force-applying rate control mechanism settable in accordance with the rates of movement of a target moving both in train an-d elevation and operable independently of said stabilizing means for applying forces to said directional mechanism to continuously direct the same at the target.

24. In a fire control instrument'subject to oscillatory movement, the combination of directional mechanism, stabilizing means partially controlling the same to compensate for the eiect upon the mechanism of angular movement-of the craft on which the instrument is mounted, rate control mechanism settable in accordance with the movement of a targetboth in train and eleviation and operable independently of said staand adjusting means to set the second named force-applying means to cause said actuating mechanism to automatically move said sighting device in accordance with the rate of movement of the target in elevation, both said variable speed mechanisms co-acting to maintain said sighting device upon the target.

26. In a re control instrument. the combination of a directing device, an operating drive for imparting va slewing movement to said device, means for automatically directing said device at a target comprising adjustable torque-applying means comprising force-developing means and regulating mechanism therefor settable in accordance with the rate of movement of the target, a gyroscope responsive to said torque-applying means, the latter being self-acting upon the gyroscope when so set, and connections between said gyroscope and directing device capable of being interrupted, and control-determining mechanism selectively operable to interrupt or maintain said connections from said gyroscope to said directing device and to eii'ect a slewing connection from said operating drive to said directing device when said connections from the gyroscope thereto are interrupted.

27. In a fire control instrument, the combination of a rotary support, a directing device movable therewith in train and independently thereof in elevation, torque-applying means settable to be self-acting in accordance with the rates of movement in train and elevation of a target having such movement, a gyroscope mounted for precession in train and elevation responsive to said controlled by said gyroscope and operatively connected to said rotary support and to said directing device, slewing mechanisms for slewing said device in train and elevation, and selective mechanisms operable to operatively combine said actuating connections from the gyroscope to said directing device to automatically and continuously direct said device upon the target, said selective mechanisms also being operable to interrupt said operative combination o! said connections to said device and to combine said slewing mechanisms 21 with said support and device for effecting the slewing oi the latter in train and elevation.

28. In a lire control instrument, the combination of a constant speed gyroscope, torque-applying means acting on said gyroscope in accordance with the rate of change of position of a target to cause corresponding precession of said gyroscope, co-acting electrical contacts controlled by said gyroscope, operating mechanism including electrical power apparatus controlled by said coacting contacts, and angularly displaceable. direc- 'tional mechanism controlled by said operating mechanism to be directed at the target.

29. In a lire control apparatus, the combination of a gyroscope, a displaceable member settable in accordance with the rate of change of a given factor, an extensible spring having an end portion secured to said member and a free end. a lever pivotally mounted on said member and connected to the free end of said spring, a second lever iixedlypivoted, the iii-st named lever being displaceable by said member along sai-d second lever to apply force to the latter, and connections from said second lever to said gyroscope to apply a torque thereto in accordance with said rate of change, said rst named lever being shaped to produce compensating changes in its effective length i'or changes in the length oi" said spring.

30. In a fire control instrument, the combination of a universally mounted constant speed gyable spring operated part settable in accordance with the rate of change of position of a target in a plurality of planes. means under the control of said settable means for causing precession of the gyroscope in accordance with said rates, a sighting device, and power actuated means controlled by connections between the gyroscope and the device for moving the device in accordance with said rates.

34. In apparatus for determining the rate of change of position of a target, the combination of a gyroscope, power actuated directional mechanism controlled by the gyroscope, means for precessing the gyroscope in a plurality of planes to maintain the mechanism directed at the target, and means including an adjustable spring operated part associated with the precessing means for indicating .the rate of change of position of the target.v

35. In a fire control instrument. the, combination of a gyroscope. means settable to be self-acting to apply torques about mutually perpendicular axes of said gyroscope to precess the same about said axes, directional mechanism, and independently operable connections between said gyroscope and mechanism controlled by the former to automatically direct said mechanism.

36. In a iire control instrument, the combination of a gyroscope, torque-applying means settaroscope, a pluralityof force-developing mechanisms each adjustable to produce a force proportional to a rate oi' 4change in an angular relation between two objects', connections controlled by said mechanisms to apply the forces developed by the latter to said syroscope to precess the same to generate the angular relation between the obi ects, and electrical mechanisms operable to generate electric current and including electro-magnetic force-applying means responsive to the generated current to modify the force produced by said first named mechanisms in accordance with variations. in the said angular relation.4

31. In a fire control instrument, the combination oi' directional mechanism, a universally mounted gyroscope. torque-applying mechanisms adiustable proportionally to rates of change in the angular relation between two objects and acting on said gyroscope to precess the same to generate the angular relation between the objects, poweractuated connections between said gyroscope and directional mechanism including electrical controls operated by said gyroscope. electric current generating means, electro-magnetic force-apply*`- ing means responsive to said current generating means to modify the force applied by said torque mechanisms to `said gyroscopeL-and-m'anual operating means controlling said electric current gen. erating means in accordance with variations in the said angular relation oi' the objects.

32. In a tire control instrument, the combination of directional mechanism@ gyroscope, power actuated means controlled by said gyroscope for directing the mechanism, a device including an adjustable springoperated part settable in accordance with the rate of change of position of a target, and means automatically operated by the device for applying a torque, to the gyroscope to cause it to precess. whereby the directional v mechanism will be maintained. accurately directed at the target.

33. In a tire control instrument, the combination of a gyroscope. means including an adjust-V ble to be self-acting to precess said gyroscope about angularly related axes, directional mechanism adjustable about angularly related axes,v

means operable under the control of said gyroscpe to direct said mechanism about its axes at a target, and auxiliary force-applying means tion of directional mechanism, a gyroscope. power actuated means controlled by said gyroscope and connected for directing the mechanism in train, a device including an adjustable spring operated part settable in accordance with the rate of change of position in train of a target, a second power actuated means controlled by said gyroscope and connected for directing the mechanism in elevation, a second device settable in accordance with the rate of change of position of the target in elevation, and means automatically operated by the devices for applying torques to the gyroscope to cause it to precess in train and elevation, whereby the directional mechanism will be maintained accurately directed at the target.

'. v HANNIBAL C. FORD.

REFERENCES CITED The following references are of record in the ille of this patent:

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